A Shrooman makes a tiny grunt when they find a target, so listening for this can prepare you to avoid them.
Shroomen cannot change directions while headbutting, making sidestepping them from a distance fairly simple.
Additionally, when they hit a wall they will stun themselves, leaving a very large window for retaliation.
Try to avoid getting caught with a Shrooman in a tight corridor. It will be much harder to avoid them this way.
If your movement speed is high enough and you have a small gap between you and an attacking Shrooman, simply walking backwards and swinging a melee weapon can defeat them very easily.
History[]
0.7.4.0-6fbe: Fixed a bug where Shroomen would not fully play their bump animation when hitting a player.